Selector switch cleaner



Dec. 29,1970 p, p, POWELL EI'AL 3,550,178

SELECTOR SWITCH CLEANER Filed March 25 1968 3 Sheets-Sheejt 1 M' PETER www vnweLL, LEoNARb Geom?. NOMS RAVON man FREMUC! LESUE ExLmazv.

lNveNrols Dec. 29, 1970 p, D, POWELL EIAL 3,550,178 A SELECTOR SWITCH CLEANER y Filed march 25, 1968 s sheets-sheet 2 YETER DAV I D NNIE LLi Lamm amas TnoMAs. mm3.

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SELECTOR SWITCH CLEANER Y Filed Maron 25, 1968 3 sheets-sheets 30 lFigli 29a PETER nAvln POWELL, A LEONARD GEBRGE THOMAS UWM "n FnEnEmtK LESLIE BELLINGEQ,

INVG HYDRS United States Patent Office 3,550,178 Patented Dec. 29, 1970 3,550,178 SELECTOR SWITCH CLEANER Peter D. Powell, 3 Maple Road, Boston, Lincolnshire, England, Leonard George Thomas Capon, Southall, and Frederick Leslie Bellinger, Hayes, England; said Capon and said Bellinger assignors to said Powell Filed Mar. 25, 1968, Ser. No. 715,914 Claims priority, application Great Britain, Mar. 29, 1967, 14,276/67, 14,378/ 67 Int. Cl. A471 Z5 00; H01h 1 60 U.S. Cl. -210 6 Claims ABSTRACT OF THE DISCLOSURE A cleaner for selector switches of the kind having banks of contacts arranged in a circular arc. A novel cleaning arm is provided for mounting in a novel bobbin which is rotated at the centre of the circular arc, the cleaning arms being thereby drawn between the contacts to clean them. The cleaning arm is a flat, spring strip of material having a cleaning portion with circular arcuate shape in the plane of the strip, the two faces of the cleaning portion having cleaning areas raised with respect to depressions therebetween, at least the cleaning areas being covered with cleaning material.

The invention relates to a cleaner for cleaning the contacts of uniselector switches. Such switches may be cleaned by a cleaning machine having, for each -bank of the switch, a bobbin which can be arranged to rotate about the switch wiper axis and which is threaded with pieces of cleaning tape each arranged to pass between, and thereby clean, contacts of a respective row in the bank as the bobbin is rotated. Usually each uniselector switch has three banks of contacts and the cleaning machine has three bobbins arranged to rotate together.

Bobbins used hitherto have had a set of radially projecting fingers for each row of contacts in the bank, the number of rows in a bank being typically eleven. A cleaning tape was interwoven between the fingers of each set and fixed at its ends to the bobbin. In such known arrangements the replacement of cleaning tapes by the removal of soiled tapes and the interweaving of clean tapes between the fingers was time-consuming and costly. Furthermore, in being interwoven b rtween the lingers the tape deflected the fingers up or down out of their normal plane so that the cleaning faces presented by the tape were not normal to the bobbin axis but were inclined slightly, resulting in uneven cleaning of the contacts. The invention seeks to relieve these disadvantages.

According to the invention there is provided a cleaning arm for a selector switch cleaner, which arm cornprises an essentially flat, springy, strip of material with a cleaning portion having, in the pla-ne of the strip circular arcuate form, the two faces of the cleaning portion having spaced cleaning areas raised with respect to depressions between the cleaning areas, the depressions of each face corresponding with the cleaning areas of the other;

and a cover of cleaning material covering at least the cleaning areas.

The cleaning portion may have a continuously curved, for example sinusoidal, form to give the depressions and relatively raised cleaning areas. Preferably, however, the cleaning areas are raised flats parallel to the plane of the strip.

The cover may be constituted by a layer of flock material adhered at least to the cleaning areas. The flock material may be adhered to the strip by adhesive or, where the strip is of thermoplastic material it may be thermally softened during application of the ock material so that the flock material adheres thereto. Preferably the flock material is sprayed on to the strip which is charged electrostatically to attract the flock material and ensure even distribution. In this way the fibres of the flock material can be attached by their ends to the strip to form a miniature brush. The whole strip may be covered with fiock material.

However, in a preferred embodiment of the invention the cover is a cleaning tape fitted as a sleeve over the strip and fixed thereto. Preferably the tape is fixed to the strip at or near only the leading end (the end which leads when the arm is swept through contacts to be cleaned) and the other end is free. This prevents ruckng of the tape at the trailing end. Alternatively for fixing the tape to the strip the side edges of the strip, preferably only the inner edge, may be provided with undercut barbs arranged to engage the sleeve to prevent its sliding off the strip from the trailing end. Such barbs allow the tape to be slipped over the strip from the trailing end.

Preferably the strip is of thermoplastic material having characteristics of strength, resilience and stiffness substantially those of the material known as nylon A100, which is the preferred material. With this type of material fixing of the tape to the strip is conveniently effected by heat sealing, the thermoplastic material being fused into the tape material =by the application of heat.

The cleaning arm is mounted, in use, in an improved bobbin and to this end the strip is preferably provided with a mounting portion which is a straight extension of the cleaning portion without the cleaning areas and depressions and turned inwardly of the circular arc. The end of the mounting portion may 'be provided with an enlarged or raised stud for engagement in the bobbin.

The bobbin is essentially cylindrical and is provided with slots spaced along its length to accommodate the appropriate number of arms. The diameter of the bobbin corresponds with the internal diameter of the cleaning portion of the cleaning arms and the interior of the slots conform with the shape of the mounting portion of the cleaning arms. The cleaning arms may be held in place by a pin passing from end to end of the bobbin and engaging the cleaning arms, the pin :being located in a hole or channel formed across the slots and -being withdrawn for removal of the arms. Preferably the pin engages in a notch formed in the outer edge of each cleaning arm and conveniently for formation of the notch and heat sealing of the strip to the tape is accomplished in the same operation, an iron with a heated bit of about the same diameter as the pin being applied to the side of the arm.

The arms may be retained by means of a spring clip on the bobbin, the clip having an engagement portion extending from end to end of the bobbin, and urged into the aforementioned channel by spring pressure. The engagement portion may be pin-like or may be constituted by the edge of a leaf spring.

In a preferred embodiment of the invention the trailing end of each cleaning arm, which is the end remote from the mounting portion, is left free when the arm is mounted in the bobbin so that the arm is free to be guided by the contacts between which it passes. 'The inner edge of the cleaning portion of each arm may be located in a respective groove in the bobbin. The arrangement is such as to allow a certain degree of self alignment of the arms as they enter the contacts.

Furthermore, the angle between the mounting portion and the leading part of the cleaning portion is such that the curve presented by the leading edge of the arm is suiiiciently gradual to avoid an abrupt build-up of torque as the arms enter the contacts. This allows the bobbin driving motor to operate without stalling.

A feature of the preferred form of bobbin is that it has end plates with projections conforming generally to the area covered by the cleaning portions of the arms.

These end plates constitute stops against which the outer arms bear and which thereby prevent any tendency for the arms, particularly the outer arms, to spread outwardly and so reduce the cleaning pressure. The bobbins may be made of steel or aluminium or the bodies of aluminium and the end plates of brass, for example. It is preferred to make the end plates separate from the body of the bobbin since the end plates are vulnerable to being bent on dropping the bobbin. If the end plates are screwed on to the bobbins replacement may be effected easily.

Alternatively, the bobbins may be made of thermoplastic material, a preferred material being glass-impregnated nylon. Such bobbins may be made by moulding a number of similar disc-like members which are bolted or high-frequency welded together in a stack.

FIGS. 1 and 2 show in plan and developed elevation a cleaning arm in accordance with the invention;

FIG. 3 is a developed elevation of another arm in accordance with the invention;

FIGS. 4, 5 and 6 show in plan side elevation and front elevation the body of a bobbin on which the cleaning arm of FIGS. 1 to 3 may be mounted;

FIG. 7 is a plan view of one of the end plates for the bobbin body of FIGS. 4 to 6;

FIGS. 8 and 9 are views corresponding to FIGS. 4 and 5 of a modified form of the bobbin;

FIG. 10 is a schematic end elevation of another form of bobbin for use in accordance with the invention;

FIG. 11 is an end elevation of another bobbin for use in accordance with the invention;

FIGS. 12 and 13 are schematic side elevations illustrating the formation of the bobbin of FIG. 11;

FIG. 14 is a plan view of a modified cleaning arm strip for an arm in accordance with the invention particularly suitable for use in the bobbin of FIGS. 1l to 13; and

FIGS. 15 and 16 are schematic illustrations showing the retaining studs of cleaning arms suitable for the bobbin of FIGS. 11 to 13.

Referring to FIGS. 1 and 2 the cleaning arm comprises a flat strip 1 of nylon A100 formed with a circular arcuate cleaning portion 2 and a straight mounting portion 3. The cleaning portion is provided with a number of spaced cleaning flats 4 on its upper and lower faces, the flats being parallel with each other and being separated by depressions 5, the depressions on one side corresponding with the flats on the other. The thickness of the material of the strip is 0.030" throughout and the overall thickness of the strip (between flats) is 01.060".

The strip 1 is covered with a hollow woven tape, shown in broken line at 6, of cleaning material, known as bank cleaning tape No. 1. The tape is applied as a sleeve over the strip 1 and is heat sealed at 7 to the mounting portion by application of a heated bit of circular section. This fuses the nylon into the tape and at the same time forms a semi-circular notch, the function of which Will be explained. The other end 8 of the tape is left free.

FIG. 3 shows in elevation an arm covered with flock material f instead of a tape 6 as in FIGS. l and 2. The flock material is swayed on to the strip which has an adhesive applied to its faces and which is maintained at a high voltage, thereby attracting the flock material to it electrostatically. This causes the fibres of the flock material is swayed on to the strip which has an adhesive applied to its faces and which is maintained at a high voltage, thereby attracting the flock material to it electrostatically. This causes the fibres of the flock material to adhere to the strip by their ends, thus forming a brushlike structure.

Referring now to FIGS. 4 to 6 there is shown the body of a bobbin on which the arm of FIGS. l to 3 may be mounted. FIG. 4 shows at 9 the position of an arm when so mounted. The bobbin body 10 is of aluminium, essentially cylindrical and has a square bore 11 whereby it is mounted on a driving shaft driven by an electric motor. In operation the bobbin is driven in the direction shown by the arrow fourteen revolutions in cleaning one bank of contacts. A selector switch having three banks of contacts is cleaned by mounting three such bobbins one above the other.

One side of the bobbin body has a number of straightbottomed slots 12 cut into it, there being thus defined positions for eleven cleaning arms, the outer arms being accommodated in slots defined in part by removable brass end plates 13 (FIG. 5). The cleaning arms are retained in their respective slots by a pin (not shown) which is accommodated in a hole 14 drilled across the slots and which engages with the notch formed at 7 in the cleaning arms.

FIG. 7 shows in detail the shape of the end plates 13, showing the projections 15 extending generally over the area occupied by the cleaning arms and serving to provide restriction against spreading of the arms.

Referring to FIGS. 8 and 9 there is shown a bobbin of the same general kind as illustrated in FIGS 4 to 6 but having a spring clip arrangement instead of a pin for retaining the cleaning arms. The spring clip is a wire clip 16 which has a straight engagement portion 17 which lodges, by spring pressure, in a channel 14a extending from top to bottom of the bobbin. The innermost part of the groove corresponds with the position of hole 14 in FIGS. 4 to 6 and the engagement portion 17 engages in the notches at 7 in the cleaning arms. The clip 16 has side portions 18 situated between the ends of the body and extending part of the way around the circumference. The end portions 18 terminate in hook portions 19 which reside in holes 20 in the ends of the bobbin. A flat 21 is formed in the bobbin so that the spring clip may be depressed inwardly as shown by the arrow P. To allow one-handed operation a link member 22 joins both end members 18. On depression of the spring clip the engagement member 17 tends to be withdrawn outwardly from the channel by rotation about points 23. This allows the cleaning arms to be withdrawn and replaced easily. Alternatively, the arrangement may be such that the cleaning arms can be withdrawn without manual depression of the spring merely by pulling the arms against the initial spring force so that the engagement member is disengaged thereby.

Another form of spring clip which may be used is illustrated schematically in FIG. 10. A bowed leaf spring 24 extends the length of the bobbin and is retained by one side in a notch 25. The other side of the leaf spring lodges normally in channel 14a. Radial inward pressure at the centre of the leaf spring draws the side from channel 14a and disengages the cleaning arms.

FIG. 11 is an end elevation of another form of bobbin. The bobbin is of glass-impregnated nylon and is of substantially the same form as those of FIGS. 4 to 10 being essentially cylindrical with a series of slots at 26. However, there are provided grooves 27 in the periphery of the bobbin, one to accommodate the inner edge of each cleaning arm. This arrangement maintains the cleaning arms in alignment while allowing a limited degree of lateral movement for self-alignment of the arms with the contacts being cleaned.

There is also shown in FIG. 11 another way of retaining the cleaning arms. Each of the slots at 26 is provided with an L shaped channel 28 formed in a wall thereof. Each channel is closed at its inner end and has a mouth at the other end opening in the side of the bobbin. The mounting portion of each arm has at its end a raised stud Z9 which is accommodated in the channel 28, as shown, the arm being inserted by manipulating the stud into the mouth of the channel and then swinging the arrn around into place.

FIG. 12 illustrates the way in which the bobbin of FIG. 11 is made. A stack of similar moulded disc-like members 30 is assembled together and high-frequency welded, although alternatively they may be glued or bolted together. It will be seen that the channel 28 is moulded into one wall of each slot. It is possible, however, to form a complementary channel in the other Wall of the slot also. As shown in FIG. 13 the members 30 may be located with respect to each other by complementary projections 31 and sockets 32.

As an alternative or as au adjunct to heat sealing the tape on to the strip, the strip may be provided with barbs which engage the tape and prevent it slipping oif. FIG. 14 shows such a strip with barbs b provided on the inner edge only. This arrangement is particularly useful where, as in the bobbin of FIGS. 1l to 13, the arms are retained by studs.

FIG. 15 shows the end of a cleaning arm having stud 29 for use in the bobbin of FIG. 1l. FIG. 16 shows an alternative form where there are complementary channels 28 in both Walls of the bobbin. The arm is provided With complementary studs 29, 29a.

The studs of the arms shown in FIGS. 15 and 16 have a diameter equal to the width of the strip. However, the studs may be of small or larger diameter.

Appropriate, but not limiting, dimensions and angles are indicated in the drawings.

The invention is not restricted to the details of the foregoing description made with reference to the drawings. For example, the tape 6 could be sealed at its free end by heat sealing onto a free piece of nylon, which piece may be moulded with strip 1 and severed therefrom by the heat sealing. In this way the end `8 of the tape would still be free to slide on the end of the strip. Furthermore, a similar procedure could be adopted for sealing the other end of the tape. Alternatively, the leading end of the tape could be sealed to the mounting portion over a wider area by the more general application of heat.

With the arrangement described above with reference to the drawings it will be seen that the interchange of cleaning arms may be made particularly quickly, it being possible, for example, to elect replacement without removing the bobbins from the cleaning machine. Furthermore, the xing of the tapes by heat sealing obviates the use of metal clips or staples for this purpose and thus the danger to the contacts thereby.

We claim:

1. A cleaning arm for a selector switch cleaner, which arm comprises an essentially flat, springy, strip of material with a cleaning portion having, in the plane of the strip, circular arcuate form, the two faces of the cleaning portion having spaced cleaning areas raised with respect to depressions between the cleaning areas, the depressions of each face corresponding with the cleaning areas of the other, and a cover of cleaning material covering at least the cleaning areas, said stripI further having a mounting portion which is a straight extension of the cleaning portion without the cleaning areas and depressions and turned inwardly of the circular arc.

2. A cleaning arm as claimed in claim ,1, wherein the cleaning areas are raised llats parallel to the plane of the strip.

3. A cleaning arm as claimed in claim 1, wherein the cover is a cleaning tape tted as a sleeve over the strip and iiXed thereto.

4. A cleaning arm as claimed in claim 1, wherein the cover is constituted by a layer of ock material adhered at least to the cleaning areas.

5. A cleaning arm as claimed in claim 4, wherein the bres of the ilock material are attached by their ends to the strip.

6. A cleaning arm for a selector switch cleaner, which arm comprises an essentially flat, springy, strip of material with a cleaning portion having, in the plane of the strip, circular arcuate form, the two faces of the cleaning portion having spaced cleaning areas raised with respect to depressions between the cleaning areas, the depressions of each face corresponding with the cleaning areas of the other, and a cover of cleaning material covering at least the cleaning areas, said cover comprising a cleaning tape tted as a sleeve over the strip and Xed thereto.

References Cited UNITED STATES PATENTS 1,584,033 5/ 1926 Kannenberg 15-97 2,301,853 11/1942 Cannon 51-170.4 2,503,558 4/1950 Mesch 15-97 2,504,709 4/1950 Lorimer 15-97 2,721,349 10/1955 Wright 15-210 3,187,362 6/1965 Garrett 15-210 WALTER A. SCHEEL, Primary Examiner L. G. MACHLIN, Assistant Examiner 

